This is a bit of a no brainer. Nanny 2 is made of metal so Magneto could crush her with a gesture. It’s no exaggeration to say that this wouldn’t even be a fight. It would be over as soon as it has begun. While that may sound pretty sad for Nanny, you can’t win every fight right? Even without the fact that Nanny is a robot, Magneto is just supremely powerful. He’s definitely an omega level mutant and there are very few fighters who can stop him 1 on 1. Magneto wins.